Details
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Bug
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Status: Resolved
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P2
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Resolution: Fixed
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None
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None
Description
See https://stackoverflow.com/questions/48090668/how-to-increase-dataflow-read-parallelism-from-cassandra?noredirect=1#comment83227824_48090668 . When CassandraIO can't estimate size, it falls back to a single split:
A single split is very poor for performance. We should fall back to a different value. Not sure what a good value would be; probably the largest value that still doesn't introduce too much per-split overhead? E.g. would there be any downside to just changing that number to 100?
Alternatively/additionally, like in DatastoreIO, CassandraIO could accept requested number of splits as a parameter.